The Xenogeneic Effect

Abstract

Abstract Modified Marbrook culture vessels with two chambers separated by a 0.2-µ porosity membrane have been utilized to show that antigen-stimulated human lymphocytes produce a soluble factor(s) which restores the ability of thymectomized, irradiated, and bone marrow-protected mice to mount a primary IgM plaque-forming cell response in vitro. In the initial experiments, the human lymphocytes plus antigen (sheep erythrocytes) were cultured in the lower chambers of the Marbrook vessels and the T celldeficient mouse spleen cells plus sheep erythrocytes were cultured in the upper chambers. The response of the spleen cells was shown to be enhanced as a function of the number of human lymphocytes in the lower chambers. In subsequent experiments, the human lymphocytes were challenged with allogeneic lymphocytes or activated with a variety of T cell mitogens. Supernatants from these cultures, when placed in the lower chambers of the Marbrook vessels, were also capable of reconstituting the antibodyforming cell response of the mouse B cells. The results of the experiments are discussed in relation to a model of B cell induction which incorporates a non-antigen-specific “helper” T cell.